byname of Greek GALENOS, Latin GALENUS (b. AD 129, Pergamum, Mysia,
Anatolia [now Bergama, Tur.]--d. c. 216), Greek physician, writer,
and philosopher who exercised a dominant influence on medical theory and
practice in Europe from the Middle Ages until the mid-17th century. His
authority in the Byzantine world and the Muslim Middle East was similarly
long-lived.

Early life and training.

The son of a wealthy architect, Galen was
educated as a philosopher and man of letters. His hometown, Pergamum, was
the site of a magnificent shrine of the healing god, Asclepius, that was
visited by many distinguished figures of the Roman Empire for cures. When
Galen
was 16, he changed his career to that of medicine, which he studied
at Pergamum, at Smyrna (modern Izmir, Tur.), and finally at Alexandria
in Egypt, which was the greatest medical centre of the ancient world. After
more than a decade of study, he returned in AD 157 to Pergamum, where he
served as chief physician to the troop of gladiators maintained by the
high priest of Asia.

In 162 the ambitious Galen moved to Rome. There he quickly rose
in the medical profession owing to his public demonstrations of anatomy,
his successes with rich and influential patients whom other doctors had
pronounced incurable, his enormous learning, and the rhetorical skills
he displayed in public debates. Galen's wealthy background, social
contacts, and a friendship with his old philosophy teacher Eudemus
further enhanced his reputation as a philosopher and physician.

Galen abruptly ended his sojourn in the capital in 166. Although
he claimed that the intolerable envy of his colleagues prompted his return
to Pergamum, an impending plague in Rome was probably a more compelling
reason. In 168-169, however, he was called by the joint emperors Lucius
Verus and Marcus
Aurelius to accompany them on a military campaign in northern Italy.
After Verus' sudden death in 169, Galen returned to Rome, where
he served Marcus Aurelius and the later emperors Commodus and Septimius
Severus as a physician. Galen's final works were written after 207,
which suggests that his Arab biographers were correct in their claim that
he died at age 87, in 216/217.

Anatomical and medical studies.

Galen regarded anatomy
as the foundation of medical knowledge, and he frequently dissected and
experimented on such lower animals as the Barbary
ape (or African monkey), pigs, sheep, and goats. Galen's advocacy
of dissection, both to improve surgical skills and for research purposes,
formed part of his self-promotion, but there is no doubt that he was an
accurate observer. He distinguished seven pairs of cranial nerves, described
the valves of the heart, and observed the structural differences between
arteries and veins. One of his most important demonstrations was that the
arteries carry blood, not air, as had been taught for 400 years. Notable
also were his vivisection
experiments, such as tying off the recurrent laryngeal nerve to show that
the brain controls the voice, performing a series of transections of the
spinal cord to establish the functions of the spinal nerves, and tying
off the ureters to demonstrate kidney and bladder functions. Galen was
seriously hampered by the prevailing social taboo against dissecting human
corpses, however, and the inferences he made about human anatomy based
on his dissections of animals often led him into errors. His anatomy of
the uterus, for example, is largely that of the dog's.

Galen's physiology was a mixture of ideas taken from the philosophers
Plato and Aristotle as well as from the physician Hippocrates, whom Galen
revered
as the fount of all medical learning. Galen viewed the body as consisting
of three connected systems: the brain and nerves, which are responsible
for sensation and thought; the heart and arteries, responsible for life-giving
energy; and the liver and veins, responsible for nutrition and growth.
According to Galen, blood is formed in the liver and is then carried
by the veins to all parts of the body, where it is used up as nutriment
or is transformed into flesh and other substances. A small amount of blood
seeps through the lungs between the pulmonary artery and pulmonary veins,
thereby becoming mixed with air, and then seeps from the right to the left
ventricle of the heart through minute pores in the wall separating the
two chambers. A small proportion of this blood is further refined in a
network of nerves at the base of the skull (in reality found only in ungulates)
and the brain to make psychic pneuma,
a subtle material that is the vehicle of sensation. Galen's physiological
theory proved extremely seductive, and few possessed the skills needed
to challenge it in succeeding centuries.

Building on earlier Hippocratic conceptions, Galen believed that
human health requires an equilibrium between the four main bodily fluids,
or humours--blood,
yellow bile, black bile, and phlegm. Each of the humours is built up from
the four elements and displays two of the four primary qualities: hot,
cold, wet, and dry. Unlike Hippocrates, Galen argued that humoral
imbalances can be located in specific organs, as well as in the body as
a whole. This modification of the theory allowed doctors to make more precise
diagnoses and to prescribe specific remedies to restore the body's balance.
As a continuation of earlier Hippocratic conceptions, Galenic physiology
became a powerful influence in medicine for the next 1,400 years.

Galen was both a universal genius and a prolific writer: about
300 titles of works by him are known, of which about 150 survive wholly
or in part. He was perpetually inquisitive, even in areas remote from medicine,
such as linguistics, and he was an important logician who wrote major studies
of scientific method. Galen was also a skilled polemicist and an
incorrigible publicist of his own genius, and these traits, combined with
the enormous range of his writings, help to explain his subsequent fame
and influence.

Influence.

Galen's writings achieved wide circulation during his lifetime,
and copies of some of his works survive that were written within a generation
of his death. By AD 500 his works were being taught and summarized at Alexandria,
and his theories were already crowding out those of others in the medical
handbooks of the Byzantine world. Greek manuscripts began to be collected
and translated by enlightened Arabs in the 9th century, and in about 850 Hunayn
ibn Ishaq, an Arab physician at the court of Baghdad, prepared
an annotated list of 129 works of Galen that he and his followers
had translated from Greek into Arabic or Syriac. Learned medicine in the
Arabic world thus became heavily based upon the commentary, exposition,
and understanding of Galen.

Galen's influence was initially almost negligible in western
Europe except for drug recipes, but from the late 11th century Hunayn's
translations, commentaries on them by Arab physicians, and sometimes the
original Greek writings themselves were translated into Latin. These Latin
versions came to form the basis of medical education in the new medieval
universities. From about 1490, Italian humanists felt the need to prepare
new Latin versions of Galen directly from Greek manuscripts in order
to free his texts from medieval preconceptions and misunderstandings. Galen's
works were first printed in Greek in their entirety in 1525, and printings
in Latin swiftly followed. These texts offered a different picture from
that of the Middle Ages, one that emphasized Galen as a clinician,
a diagnostician, and above all, an anatomist. His new followers stressed
his methodical techniques of identifying and curing illness, his independent
judgment, and his cautious empiricism. Galen's injunctions to investigate
the body were eagerly followed, since physicians wished to repeat the experiments
and observations that he had recorded. Paradoxically, this soon led to
the overthrow of Galen's authority as an anatomist. In 1543 the
Flemish physician Andreas Vesalius showed that Galen's anatomy of
the body was more animal than human in some of its aspects, and it became
clear that Galen and his medieval followers had made many errors.
Galen's
notions of physiology, by contrast, lasted for a further century, until
the English physician William Harvey correctly explained the circulation
of the blood. The renewal and then the overthrow of the Galenic tradition
in the Renaissance had been an important element in the rise of modern
science, however.

BIBLIOGRAPHY.

English editions with commentaries of Galen's major works include
Margaret Tallmadge May (trans.), Galen on the Usefulness of Parts
of the Body, 2 vol. (1968); Phillip De Lacy (ed. and trans.), On
the Doctrines of Hippocrates and Plato, 3 vol. (1978-84); Vivian Nutton
(trans.), On Prognosis (1979); Richard Walzer and Michael Frede
(trans.), Three Treatises on the Nature of Science (1985); and Albert
Z. Iskandar (trans.), On Examinations by Which the Best Physicians Are
Recognized (1988). The selection of passages in Arthur J. Brock, Greek
Medicine, Being Extracts Illustrative of Medical Writers from Hippocrates
to Galen (1929, reprinted 1977), still offers the best sampling
of Galen's own writings.

Owsei Temkin, Galenism: Rise and Decline of a Medical Philosophy
(1973), is fundamental. Rudolph E. Siegel, Galen's System of
Physiology and Medicine (1968), Galen on Sense Perception
(1970),
and Galen on Psychology, Psychopathology, and Function and Diseases
of the Nervous System (1973), attempt to reconcile Galen
with
modern medicine. Shorter accounts include sections in two essays by Vivian
Nutton, "Roman Medicine, 250 BC to AD 200," and "Medicine in Late Antiquity
and the Early Middle Ages," chapters 3-4 in Laurence Conrad
et al.,
The Western Medical Tradition: 800-1800 A.D. (1995); and Simon Swain,
"Galen," chapter 11 in his Hellenism and Empire: Language, Classicism,
and Power in the Greek World, AD 50-250 (1996), pp. 357-379. (Vivian
Nutton)